Separation of Silica from Rice Straw to Improve Its Hydrolysis for Ethanol Production

Rice straw is an inexpensive and easily accessible lignocellulosic resource which in comparison with other lignocellulosic materials has high content of silica. The presence of silica reduces enzymatic hydrolysis yield of straw and consequently, adversely affects ethanol production. In this study, silica removal from rice straw using various chemical substances at different temperatures and time intervals was investigated. Sodium carbonate, sodium hydroxide, sodium chloride, and sodium dodecyl sulfate were used to remove silica from rice straw. Sodium carbonate and sodium hydroxide were more effective in separation of silica. Moreover, temperature and time interval of pretreatment had pronounced effect on silica removal.. Extending pretreatment time at higher temperatures led to more efficient silica separation and hydrolysis. Afterwards, enzymatic hydrolysis of the pretreated straw was carried out to investigate the effect of pretreatment and silica removal on hydrolysis efficiency. The hydrolysis of the pretreated straw using sodium carbonate and sodium hydroxide showed better improvement.

Keywords: rice straw, silica, enzymatic hydrolysis, separation, pretreatment